Character triangle pattern ('*')

What this problem practises

Loops are where off-by-one bugs live. range() excludes its stop value, the loop variable keeps its last value even after the loop ends, and break versus continue changes the flow in ways that are easy to misread when you skim.

This is an output-prediction problem: read the snippet carefully and write down exactly what it prints before anything runs. These questions are interview staples because they test whether you know the language rules, or merely recognise their syntax.

Difficulty: easy — the fix or the trick is normally a single line, and a careful read should be enough.

The challenge

What will this program print? Type the exact output (all lines).

The code runs in PyDebug’s in-browser compiler. Open the problem, run the snippet, watch the exact error or output, and keep iterating until it is right. Signed-in solves count toward XP and your daily streak.

The snippet

The interactive editor pre-fills exactly this code — read it, then submit your prediction:

for i in range(1, 5):
    print('*' * i)

More loops problems

• IndexError: loop runs past a short list easy
• TypeError: looping directly over a number easy
• TypeError: range('8') gets text easy

Keep going

• Output-prediction strategies — how to predict tricky snippets without running them.
• Browse every loops problem in this topic.
• Common Python errors and what they actually mean, plus the Python glossary for any term used on this page.